Integrated circuits in general, and CMOS devices in particular, continue to gain wide spread use as the demands for increased functionality and enhanced benefits continue to enlarge. In order to meet these demands, the integrated circuit industry continues to develop new circuit structures that enhance capabilities and extend the use of existing fabrication processes and equipment.
Key to the fabrication of integrated circuits is the ability to construct highly reliable and low resistance connections between the individual semiconductor device terminals themselves, and other needed circuit components including various power supplying and common signal carrying conductor structures (buses) The industry often refers to connections made directly to a semiconductor device terminal as a contact (or windows) and connections made between other conductor structures as vias.
One issue that has recently started to plague the industry as the conductive structures have become more exotic and reduced in size, is that of stress migration. It is believed that stress migration grows by coalescence of vacancies, driven by a mechanical stress gradient, and appropriate temperatures. Eventually, over a period of time that is hard to predict, the stress migrations often result in open circuits. Whether the integrated circuits are copper, aluminum, or tungsten based, stress migration is a real issue.
Accordingly, what is needed in the art are interconnect structures that do not experience the stress migration issues experienced by the prior art interconnect structures.